Overview
This lecture focuses on EKG criteria for diagnosing right ventricular hypertrophy (RVH), bundle branch blocks, biventricular hypertrophy, and distinguishing EKG patterns in conditions like lung disease and cardiac amyloidosis.
Bundle Branch Blocks: Diagnosis and Criteria
- Complete bundle branch block: QRS >120 ms (per ACC criteria).
- Incomplete bundle branch block: QRS 110–120 ms.
- QRS <110 ms is not considered a bundle branch block.
- Non-specific intraventricular conduction delay: QRS >110 ms without features of right or left bundle branch block.
Right Ventricular Hypertrophy (RVH): EKG Features
- RVH requires right axis deviation (RAD) usually >+90°.
- Big R wave or R > S or R >7 mm in V1 are key criteria.
- QR or monophasic R in V1 indicates severe RVH (pressure overload).
- RVH often presents with secondary T wave inversion and/or ST depression (strain pattern) in V1–V3.
- RSR' pattern in V1 with QRS <110 ms and RAD suggests RVH.
Right Bundle Branch Block (RBBB) & Overlaps with RVH
- RSR' in V1 with QRS >110 ms is RBBB (incomplete if 110–120 ms, complete if >120 ms).
- RBBB alone does not cause right axis deviation.
- RBBB with RAD suggests RVH or left posterior fascicular block (LPFB), most often RVH.
- RBBB with R' > S and RAD is highly suggestive of RVH, but not specific.
LVH, Biventricular Hypertrophy, and Strain Patterns
- Biventricular hypertrophy: Presence of both LVH (Sokolow-Lyon/Cornell criteria) and RVH features, or paradoxically small S in V1.
- LVH strain: ST depression and T wave inversion, usually more pronounced than in RVH.
- Cat's Whisker sign: Tall R and S waves in mid-lateral precordial leads (>50 mm) indicate biventricular hypertrophy.
- LVH with right axis deviation strongly suggests biventricular hypertrophy.
Lung Disease Patterns vs. RVH
- Lung disease pattern: Right axis deviation and small R, big S waves throughout precordial leads with low voltage.
- To diagnose RVH on top of lung disease, look for large R or small S in V1, rsR' pattern, strain pattern, or T inversion in V1–V2.
Other EKG Entities and Differentials
- Early R wave transition (big R in V1/V2): Can indicate RVH, RBBB, posterior MI, WPW, or be a normal variant.
- Amyloidosis: Low voltage in limb leads, extensive pseudo-Q waves, normal or thick septum on echo.
Key Terms & Definitions
- QRS duration — Width of the QRS complex, used to define bundle branch blocks.
- RSR' pattern — QRS morphology in V1 indicative of RBBB or RVH.
- Right Axis Deviation (RAD) — QRS axis >+90°, key for RVH.
- Strain pattern — ST depression/T inversion, indicates ventricular hypertrophy.
- Cat's Whisker sign — Tall R and S waves in V4–V6, seen in biventricular hypertrophy.
- Cornell/Sokolow-Lyon criteria — Voltage criteria for diagnosing LVH.
- Pseudo-Q waves — Q-like waves in amyloidosis due to electrically inert tissue.
Action Items / Next Steps
- Review voltage and axis criteria for diagnosing RVH and LVH.
- Practice systematic EKG interpretation: Q waves, QRS width, height, and transition.
- Know differential diagnoses for early R transition and low voltage EKGs.
- Read assigned materials on bundle branch blocks, RVH, and cardiac amyloidosis.